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.\" 1.0 of the CDDL.
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.\" Copyright 2015 Joyent, Inc.
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.Dd May 02, 2020
.Dt PSTOPSTATUS 3PROC
.Os
.Sh NAME
.Nm Pdstop ,
.Nm Pstopstatus ,
.Nm Pstop ,
.Nm Pwait ,
.Nm Ldstop ,
.Nm Lstop ,
.Nm Lwait
.Nd process and thread stop operations
.Sh LIBRARY
.Lb libproc
.Sh SYNOPSIS
.In libproc.h
.Ft int
.Fo Pdstop
.Fa "struct ps_prochandle *P"
.Fc
.Ft int
.Fo Pstopstatus
.Fa "struct ps_prochandle *P"
.Fa "long request"
.Fa "uint_t msec"
.Fc
.Ft int
.Fo Pstop
.Fa "struct ps_prochandle *P"
.Fa "uint_t msec"
.Fc
.Ft int
.Fo Pwait
.Fa "struct ps_prochandle *P"
.Fa "uint_t msec"
.Fc
.Ft int
.Fo Ldstop
.Fa "struct ps_lwphandle *L"
.Fc
.Ft int
.Fo Lstop
.Fa "struct ps_lwphandle *L"
.Fa "uint_t msec"
.Fc
.Ft int
.Fo Lwait
.Fa "struct ps_lwphandle *L"
.Fa "uint_t msec"
.Fc
.Sh DESCRIPTION
The
.Fn Pstopstatus
function allows the caller to stop and optionally wait for the process
handle referred to by
.Fa P
to be stopped.
Stopping a process causes all of its threads to stop execution.
Where in their execution the threads will halt is not defined.
Threads may be resumed with
.Xr Psetrun 3PROC
and
.Xr prun 1 .
.Pp
The
.Fa request
argument should be one of the following symbols:
.Bl -tag -width Dv -offset indent
.It Dv PCSTOP
Stop the process; wait for completion before returning.
.It Dv PCDSTOP
Stop the process; do not wait for completion before returning.
That is, the stopping of the process is performed asynchronously in
relation to the caller.
.It Dv PCWSTOP
Do not direct the process to stop; simply wait for it to stop.
.It Dv PCNULL
Do not direct the process to stop; simply refreshes the state of the
process.
.El
.Pp
Both the
.Dv PCSTOP
and
.Dv PCWSTOP
requests allow an upper bound on the amount of time to wait for the
process to stop.
The
.Fa msec
argument indicates the number of milliseconds to wait for the stop to
complete.
If the value of
.Fa msec
is
.Sy 0 ,
then it will wait forever.
Callers should pass
.Sy 0
for
.Fa msec
when the request is
.Dv PCDSTOP
or
.Dv PCNULL .
.Pp
When a non-zero timeout is specified, the process may or may not be
stopped upon return.
The return value does not reflect the current state of the process.
For example, if the timeout expires during a
.Fa PCWSTOP
request, the return value will be
.Sy 0
regardless of the actual state of the process.
.Pp
Only active processes may be stopped.
Handles that refer to core files, zombie processes, or files cannot be used;
unless the value of
.Fa request
is set to
.Dv PCNULL .
.Pp
The
.Fn Pstop
function is is equivalent to calling the
.Fn Pstopstatus
function with the request set to
.Dv PCSTOP .
.Pp
The
.Fn Pwait
function is is equivalent to calling the
.Fn Pstopstatus
function with the request set to
.Dv PCWSTOP .
.Pp
The
.Fn Pdstop
function is is equivalent to calling the
.Fn Pstopstatus
function with the request set to
.Dv PCDSTOP .
.Pp
The
.Fn Ldstop ,
.Fn Lstop ,
and
.Fn Lwait
functions are equivalent to the
.Fn Pdstop ,
.Fn Pstop ,
and
.Fn Pwait
functions, respectively.
Except, rather than operating on a process, they operate on the thread handle
.Fa L .
A call to
.Fn Lstop
stops only a single thread; whereas
.Fn Pstop
stops every thread in the process.
.Sh RETURN VALUES
Upon successful completion, the
.Fn Pdstop ,
.Fn Pstopstatus ,
.Fn Pstop ,
.Fn Pwait ,
.Fn Ldstop ,
.Fn Lstop ,
and
.Fn Lwait
functions return
.Sy 0 .
Otherwise,
.Sy -1
is returned and
.Dv errno
is set to indicate the error that occurred.
.Sh ERRORS
For a full list of possible errors see the
.Sy DIAGNOSTICS
section in
.Xr proc 5 .
.Pp
The
.Fn Pdstop ,
.Fn Pstopstatus ,
.Fn Pstop ,
.Fn Pwait ,
.Fn Ldstop ,
.Fn Lstop ,
and
.Fn Lwait
functions will fail if:
.Bl -tag -width Er
.It Er EAGAIN
Control over the handle
.Fa P
was lost.
Callers should call
.Xr Preopen 3PROC .
For more information on losing control, see
.Sy PROGRAMMING NOTES
in
.Xr proc 5 .
.It Er ENOENT
The request was not
.Dv PCNULL
and the process handle
.Fa P
does not refer to an active process, but refers to a core file, a zombie
process, or a file.
.It Er EINVAL
.Fa request
is not valid or the process is in an unknown state.
.It Er EPROTO
A fatal protocol error occurred and the process could not be stopped.
.El
.Sh INTERFACE STABILITY
.Sy Uncommitted
.Sh MT-LEVEL
See
.Sy LOCKING
in
.Xr libproc 3LIB .
.Sh SEE ALSO
.Xr libproc 3LIB ,
.Xr Lgrab 3PROC ,
.Xr Pcreate 3PROC ,
.Xr Pgrab 3PROC ,
.Xr Pgrab_core 3PROC ,
.Xr Pgrab_file 3PROC ,
.Xr proc 5
